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Blushing Rosette - Abortiporus biennis

Good afternoon, friends,

Happy Indigenous Peoples' Day and Columbus Day Observed (per my Audubon bird calendar Traditional Columbus Day is on 10/12, but I'm off work today so I'll take it). This week's mushroom is Abortiporus Biennis, commonly known as the blushing rosette. I first encountered this mushroom on 9/21/2021 in the ramble and we were able to visit it again on our mushroom walk this past Saturday. The first picture and the fifth picture were taken seventeen days apart. I had trouble identifying this mushroom but fortunately the former president of the New York Mycological Society, Tom Bigelow, was able to ID this for us on iNaturalist so we can learn about it today.


A. biennis is saprobic (consumes the dead wood) on hardwoods and more infrequently conifers (evergreen trees like pines and spruces). If you look at the first picture this mushroom appears to be growing out of the soil, and that's why it's important to try and dig up the entire base of the mushroom to determine whether it is in fact growing out of soil, or as is the case here, growing from buried wood. It is found in temperate forests across the northern hemisphere, predominantly North America and Europe, in the summer and fall (occasionally it's found in winter/spring in warmer climates). It causes a white rot - consumes the lignin in plant cell walls - in dead wood and dead tree roots. It is capable of producing asexual spores (genetically identical, clones) and sexual spores (genetically unique) which always fascinates me. Additionally, I incorrectly stated this mushroom had teeth on the walk on Saturday, but it does in fact have pores. The pores are what the mushroom uses to release its spores (spores are to mushrooms as seeds are to plants).

Fun Facts

This could've gone in the ecology section but I think it's so neat it deserves its own paragraph. A. biennis has two different physical structures, and both are featured in the pictures. The traditional form is seen in the first picture and the "aborted" form is seen in the fourth picture. Like hen of the woods (G. frondosa) last week, A. biennis forms a rosette when it grows traditionally. It is not understood why it also creates an aborted form which does not have the same cap nor physical structure as the rosette. There are different species of fungi that will abort a mushroom if it is infected with a parasite or other ailment. The common name, blushing rosette, comes from the color on the top of the mushroom which can vary from off-white to pinkish/reddish to brown. The red droplets seen on the third and fourth pictures are called guttation. Guttation in mushrooms is mysterious. It's thought to be a waste biproduct of digestion, but some species reabsorb nutrients from their guttation so it could also be used as storage for extra nutrients/water. Further, a lot of interesting, novel compounds are contained in this liquid exudate; for example, penicillin is found in the guttation of mushrooms in the genus penicillium. The fourth reference does a really nice job covering the different aspects of these mysterious excretions.

Big Announcement

First, we had nine people show up to the walk on Saturday. We walked around the ramble for three hours while learning about, and interacting with, all sorts of fungi. Some people may have even learned something. Thank you to everyone who showed up and hopefully we can do another walk again soon.

Last week I announced that I had big news I would unveil today, the one-year anniversary of Mushroom Monday (like Columbus Day, the actual anniversary is tomorrow, 10/12, but this is my 52nd newsletter so we're celebrating today). I want to thank everyone for their interest and readership over the past year, and we've blossomed into a community quickly approaching 150 people. After collecting all these emails over the past year, I'm excited to inform you I've sold all this information to the multinational telecommunications conglomerate AT&T. Just kidding, we're launching a website! Checkout to see all the archived newsletters since our inception one year ago.

I have to give the biggest shoutout ever to my partner, Ciara, for making this entire website. She did 99% of the legwork (converting the images to make them web ready, creating the pages, and several other website tasks that I don't know exist) and I'm deeply grateful for her. There is a signup function that sort of works, so if you want to send it to people who may be interested, they can sign up to receive the newsletter as well. For the time being I will still be sending Mushroom Monday from this email, but in the near future I hope to have a more formal listserv where I don't have to manually enter everybody's email address each week. Some of you may have noticed that you have received MM some weeks and have not received it other weeks and that's just due to me accidentally not entering your email address that week (welcome back, Sharon).

A deep thank you to each and every one of you for the continuous love and support,



1) Kuo, M. (2019, October). Abortiporus biennis. Retrieved from the MushroomExpert.Com Web site:


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